(SOLVED) carveing irregular holes inside curved surfaces

Hi. Im working on a sci-fi project at the moment. I could fake everything and use normal maps, floating geo etc… but Im curious about subd method. How do you carve in details in a curved surface preserving details?, for example one of the sides of a curved pilar (subsurfaced).

I tried a lot of things and even though bevel by hand does work perfectly for squary things or straight things If I try to make a form like a serpent It makes a mess with triangles. Should I subdivide more geometry? I think may be I need the amount of detail on that particular face but whould be a waste of geo to subdivide everything 2 or 3 times just to get the “squares” I need in that face.

As you can see on the image, sub is off, but when activated it destroys all irregular shapes, even using the knife tool.


Thats impossible what you are trying to do. You need more subdivisions like you said. That much that it is enough to model the shape in a good resolution. Otherwise you will have allways that triangle problems. Best way maybe is to cut the highpoly mesh and retopo it until it fits to what you need.


You can subdiv only one Face…And use Displace or model Your shape on that face.

One face subdiv - Displace is a picture…Only prob if , is Size…:slight_smile:

Ohhh…Forgot If You don’t need it to be smooth You can use the Carver addon…Should be in Master…
Think it’s a lot better than My first solution…:slight_smile:


ah… o.k. you need that high detail. Then you are on the right way with creating normal maps.


Yes I came to the conclusion that using subdiv you need support edges all around the area and also in external areas, because of triangles, so in the end you need a pretty subdivided mesh for perfect detail.

The other way around is using displacement, or using floaters+ normal maps.

you only need enough geometry to retain your curved lines, sub-d the surrounding face is no longer required, we have ngons and custom normals now( technically speaking in subd modelling ngons and tris are taboo, and if this was an organic or deforming animation object you should avoid them, but since the object is static and the surrounding surface around your snake line is flat it doesn’t matter and strict adherence to purist conventions is silly) the only thing you really have to avoid is overlapping tris. Knife cut the main face strategically where the snake changes direction will allow bevels etc.

I’m not saying modelling the details is the best option, just saying it is definitely possible and no big deal.

Things to consider: final display format, level of detail, is it for in-game, animation or static image?

I agree with Zenitor… ngons will not pose any problems if you subdiv that one face, since it’s a flat surface.

Thanks. the problem is that the object Im doing is curved (a futuristic pillar) at the sides so as I use knife on the face thin triangles produce artifacts at high resolution.


first image, I cut a Knife form just on place, then with alt+F fill without Ngons. Then Extrude inside for the hole and last bevel the border edges. As you can see, thin triangles and subsurf are not good friends. Should I use N-gons? I pretend to normal map everything (its for an unity project) But I would like to have it all in whole geometry if possible.

Thanks everyone.


Ok, so, adding cross section loops fixed it (one loop vertical and one loop horizontal around the knifed area). So The solution looks like adding loops one by one until you get the needed tension to avoid pinching around the interested area. So “more geo” works, but little by little. What do you think? :smiley:

That looks very good!

Sorry just realized you are using subdivision surface, stop that, stop that right now.
If your aiming at game assets use beveled edges, mean creases and edge/normal smoothing workflow.

1, random messy ngon
2, using blender4web selecting large faces and setting face normal smoothing
3, blender standard smooth shading

free blender4web works nicely, there are other normal editing addons, about.

check your tris count in unity using bevels etc vs subdivision :slight_smile: , you can also greatly reduce polycount by using edge smoothing techniques, in some places you can do without bevels completely.


If the goal is to have the detail on a normal map, you don’t have to model it in the main mesh. Could use floating geometry above the main mesh and bake that. https://vimeo.com/22154620

Thanks Again, specially Zenitor for your help.

I know what you mean. My goal is NOT to use this model with subsurf and all those triangles and bevels. The goal is to learn how to make a subd high poly mesh because Im not used to it.

Of course on a final model, I would use normal maps. I’ve been lowpoly modeling for more than 7 years and have no problems with it. Its just that I prefer to learn how to model high poly properly (well more or less, doing sub-d modelling perfectly is a daunting task) then bake maps and do the lowpoly models.

And may be it is more comfortable to have everything on one or two models, than having all the geo floating around :smiley:

I see majority of people use floating geo now. But I just wanted to learn how to do everything by cutting real geometry.


pd. BTW, my problem had to do with tension. Cutting edges where loopcut LEAVES THEM, so you dont break the natural mathematical tension of edges, doing it like that everything is perfect. If you cut edges and move them around, thin triangles and artifacts appear, because you are breaking the natural areas needed for support geo.

pd2. I experimented. Even carving rectangular holes at very sharp angles works perfectly, just cutting a pair of cross form loops around makes everything the needed tension and shape. Here is the final result with low resolution.

What used to trip me up was working from low poly simple areas towards the high poly detail region, you start off with a cube or plane and the natural inclination is to work from a basic mesh and try to build detail from larger quads.
But if you create the high poly cage required to retain the detail in the complicated areas first and flow it into the larger simple areas it suddenly becomes much easier, bevels and insets are great, it’s just arranging the direction, flow and termination when moving from transitioning planes.

With Subd you are using a low poly cage to manipulate a high poly mesh, the low poly cage is quads, but quads are just 2 triangles joined with an invisible hinge, the goal is to keep all quads flat and have all transitions along the low poly cage edges( edge loops etc, anywhere 2 or more non planar surfaces hit ) and increase detail to retain shape and avoid overlaps.

I find creating the detail and leaving the large simple areas as ngons, then quading up the ngons working from the high detail area to low is easier than trying to retain quads from the start. Hope that makes sense :slight_smile:

Similar to what I did in the past and still do today since ngons were implemented. When fixing for all quads I cut all needed forms and faces with knife tool, then dissolve the disturbing faces. The retaining geo usually is a very simple problem.

At the end of the day its easier to model using floating geo or using a high poly detail and optimizing later. Cool.

Thanks for that insight, Zenitor!